Input and Output Harmonic Suppression Strategy of Single-Phase AC–DC–AC Converter

This article presents the input harmonic current suppression strategy and the output harmonic voltage suppression strategy of a single-phase ac–dc–ac converter to maintain better power quality. First, the mechanism of dc-link voltage ripple generation and the influence of dc-link voltage ripple on rectifier and inverter are analyzed in this article. Through analysis, it can be seen that fluctuant power generates significant dc-link voltage ripple. Dc-link voltage ripple not only causes the input harmonic current of the single-phase ac–dc–ac converter, but also causes the output harmonic voltage of the single-phase ac–dc–ac converter, and the third harmonic is the most obvious. Therefore, the input harmonic current suppression strategy and the output harmonic voltage suppression strategy are designed for the rectifier and inverter, respectively. For the rectifier, a notch filter is added in the outer voltage loop to prevent the voltage ripple from affecting the input current, and the harmonic current suppression loop combined with the third harmonic current suppression loop is proposed to reduce the input harmonic current. For the inverter, the harmonic voltage suppression loop combined with the third harmonic voltage suppression loop is designed to suppress the output voltage harmonic. Simulation and experimental results show that low input harmonic current and low output harmonic voltage are achieved with the proposed harmonic suppression strategies.